Elephant seals reveal glacier melt damage
Three intrepid elephant seals have given scientists new insights into how the melting of ‘‘doomsday’’ glaciers is transforming the Antarctic.
A study from the University of East Anglia is the first to map how the water that melts from beneath the continent’s floating ice shelves behaves during winter. The shelves play a critical role in buttressing the Antarctic ice sheet, slowing the flow of its grounded ice into the Amundsen Sea in western Antarctica.
The study reveals that more meltwater from the Pine Island Glacier, one of the area’s largest, is reaching the surface of the surrounding sea than was known. This is transforming the local climate in ways yet to be incorporated in forecasting models.
The work used data collected by three wild elephant seals that were fitted with devices to track how deep they travelled underwater, how salty the water was, and its temperature. The seals can spend 90 minutes underwater at depths of up to 1500 metres.
Yixi Zheng, who led the study, said meltwater was warmer and fresher than seawater, and had a ‘‘fingerprint’’. From the seal data, she and her colleagues were able to show that the meltwater gathers in two distinct layers, one in the upper 250m, the second at 450m deep, joined by scattered meltwater-rich columns.
The relatively buoyant meltwater carries heat that enlarges the patches of open water at the edge of the glacier. It also transfers nutrients, such as iron, into the sea, which likely to fuel the growth of algae, providing food for other creatures and further altering the ecology of the region.